With the development of information communication technologies and semiconductor technologies, various types of electronic devices have been developed as multimedia devices that provide various multimedia services. For example, a portable electronic device can provide various multimedia services such as a broadcasting service, a wireless Internet service, a camera service, and a music reproduction service.
In general, a message application running in the electronic device provides one compose window to one chat room. Further, a user can write a message on the basis of various message transmission types (a Short Message Service (SMS), a Multimedia Messaging Service (MMS), and an Instant Message (IM)) or various transmission identifiers (an identifier (ID), a phone number, and a Subscriber Identity Module (SIM)). However, since a message application does not separately support a compose window for each transmission type or each transmission identifier, it is difficult for a user to change a message transmission type or a transmission identifier while the user writes a message on the basis of a specific message transmission type and a specific transmission identifier. This is because it is difficult to perform conversion during message composing as transmission formats and protocols are different from each other when message transmission types are different from each other. For example, when a transmission type changes from an IM supporting a text having 10000 characters to an MMS, the MMS maximally supports 2010 characters (example), and thus, it is unavoidable to perform cutting for a text having 2010 characters or more.
Further, since a message application according to the related art has one message compose window for each chat room, it is difficult to temporarily store a message (draft message) for different transmission identifiers. In general, the draft message is restored on the message compose window. Therefore, one compose window cannot store a draft message for each transmission message type and each transmission identifier. For example, an electronic device supporting multi-SIMs cannot distinguishably store a temporarily stored message for SIM 1 and a temporarily stored message for SIM 2. This fact is a problem occurring since only one compose window is provided to the chat room.